drm/i915/selftests: Exercise potential false lite-restore

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If execlists's lite-restore is based on the common GEM context tag
rather than the per-intel_context LRCA, then a context switch between
two intel_contexts on the same engine derived from the same GEM context
will perform a lite-restore instead of a full context switch. We can
exploit this by poisoning the ringbuffer of the first context and trying
to trick a simple RING_TAIL update (i.e. lite-restore)

v2: Also check what happens if preempt ce[0] with ce[1] (both instances
on the same engine from the same parent context) [Tvrtko]

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191002183459.26614-1-chris@chris-wilson.co.uk

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Chris Wilson 2019-10-02 19:34:59 +01:00

parent f21e8b80b7

commit fcde8c7eea

2 changed files with 194 additions and 4 deletions

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18

drivers/gpu/drm/i915/gt/intel_lrc.c

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180

drivers/gpu/drm/i915/gt/selftest_lrc.c

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